In a power generation facility and the like that uses a turbo machine such as a steam turbine, various protection apparatuses for detecting phenomena such as an abnormal rise of an rpm (rotation speed), an extension difference, an oscillation enlargement, a high temperature in a low-pressure evacuation (exhaust) chamber, lowering of a bearing hydraulic pressure, lowering of a discharge pressure of a main oil pump, and a failure of a boiler/power generator and preventing accidents from occurring or minimalizing damages due to the accidents are provided.
For example, a hydraulic system of a steam valve apparatus as follows is disclosed. Specifically, in addition to a case where an rpm of a normally-driven steam turbine is increased to a set rpm or more, an anomaly (abnormality) of the steam turbine is detected at an anomaly (abnormality) detection portion of a protection apparatus. The anomaly detection portion generates an electric signal, and a main steam stop valve set at a steam inlet of the steam turbine is closed based on the signal so that a steam influx to the steam turbine is blocked.
Hereinafter, the structure of the power generation facility of the related art will be described with reference to FIG. 3.
It should be noted that the steam valve apparatus described below is a collective term for, for example, a main steam stop valve, a governor valve, a reheat steam stop valve, and an intercept valve that are set in the steam turbine.
In FIG. 3, a steam discharged from a boiler 100 passes through a main steam stop valve 101 and a governor valve 102 and enters a high-pressure turbine (HT) 103. After an expansion work in the high-pressure turbine (HT) 103, the steam returns to the boiler 100 via a check valve 104.
After that, the steam heated by a reheater (RH) enters a medium-pressure turbine (MT) 107 via a reheat steam stop valve 105 and an intercept valve 106. The steam undergoes an expansion work in the medium-pressure turbine (MT) 107 and enters a low-pressure turbine (LT) 108 to additionally undergo an expansion work. The steam that has undergone the expansion work in the low-pressure turbine (LT) 108 is changed into water in a condenser 109 and supplied to the boiler 100 again after being pressure-raised in a feed pump (FP) 110 (steam circulation). The high-pressure turbine (HT) 103, the medium-pressure turbine (MT) 107, and the low-pressure turbine (LT) 108 are coupled to the same axis as a power generator (not shown) to drive it.
The plant shown in FIG. 3 is structured as follows to raise an operation efficiency of the plant. Specifically, a high-pressure turbine bypass valve 111 is set between an upstream side of the main steam stop valve 101 and an inlet side of the reheater (RH) of the boiler 100, and a low-pressure turbine bypass valve 112 is set between an outlet side of the reheater (RH) and the condenser 109. As a result, irrespective of whether the turbine is driven or not, circulation drive of a boiler system alone can be performed.
It should be noted that FIG. 3 shows an example of a typical steam turbine power generation facility. It is also possible to use a uniaxial or multi-axial combined cycle power plant by combining a gas turbine (not shown) with the steam turbine power generation facility and replacing the boiler 100 with an exhaust heat recovery boiler.
The power generation facility shown in FIG. 3 includes various protection apparatuses for preventing accidents from occurring in the power generation facility or minimalizing, in case of accidents, damages due to the accidents. The protection apparatuses detect phenomena such as an abnormal rise of a turbine rpm (rotation speed), an increase in an expansion of a turbine shaft length, an oscillation enlargement, a temperature rise in a low-pressure evacuation chamber, lowering of a bearing hydraulic pressure, lowering of a discharge pressure of a main oil pump, and a failure of a boiler/power generator.
For example, in a case where an rpm of a normally-driven turbine is increased to a set rpm or more and a case where other turbine anomalies occur, an anomaly (abnormality) detection portion detects the anomaly and outputs an electric anomaly (abnormality) signal. The anomaly signal is transmitted to high-speed operation electromagnetic valves 21 and 22 set in a hydraulic drive apparatus 20 of a main steam stop valve 200 shown in FIG. 4, for example.
Hereinafter, the structure of the hydraulic drive apparatus 20 of the main steam stop valve 200 will be described with reference to FIG. 4. FIG. 4 shows a structure of a hydraulic drive system of the main steam stop valve that blocks energy from entering the steam turbine as an example of the main steam stop valve 200.
In FIG. 4, the steam valve (steam valve apparatus) 200 includes a main valve 201, a piston 202, a hydraulic cylinder 203, a lower cylinder 204, an upper cylinder 205, and a hydraulic system 206. The hydraulic cylinder 203 is a double-action type and the inside thereof is sectioned into the lower cylinder (valve-open-side chamber (first chamber)) 204 and the upper cylinder (valve-close-side chamber (second chamber)) 205 by the piston 202. The hydraulic cylinder 203 includes, on both the valve-open side and the valve-close side, inlet and outlet ports for a hydraulic oil (hydraulic liquid). The hydraulic system 206 is equipped with a hydraulic pipe (also called oil passage (or passage)) and various valves and connects the lower cylinder 204 and the upper cylinder 205 to a hydraulic pressure generator and an oil tank (not shown). It should be noted that the piston 202, the hydraulic cylinder 203, and the hydraulic system 206 constitute the hydraulic drive apparatus 20 of the steam valve 200.
In the main steam stop valve 200, a valve position can be controlled using a servo valve 25 to be described later. As the main steam stop valve 200, a valve in which a sub valve is incorporated for controlling a steam flow amount at the time of activation and the like can be used.
A steam pressure acts on an upstream side of the main valve 201 of the main steam stop valve 200. Due to the hydraulic oil accumulated in the lower cylinder 204 located at a lower portion of the hydraulic cylinder 203 that accommodates the piston 202 coupled to the main valve 201, a hydraulic pressure acts on the lower portion of the piston 202. As a result, the main valve 201 is opened over the steam pressure.
On the other hand, when an anomaly (abnormality) occurs in the steam turbine, the main valve 201 is closed by discharging the oil accumulated in the lower cylinder 204 of the piston 202.
In FIG. 4, the hydraulic oil 26 is supplied from the hydraulic pressure generator (not shown). The hydraulic oil 26 is first split into two hydraulic pipes pl1 and pl2 at an inlet-side branch point J1 of the hydraulic system 206 surrounded by dashed lines. The hydraulic pipe pl1 is connected to a first oil filter 27, and the hydraulic pipe pl2 is connected to a second oil filter (oil filter dedicated to servo valve) 28. The hydraulic oil that has entered the first oil filter 27 from the hydraulic pipe pl1 is additionally split into two hydraulic pipes pl3 and pl4 at an outlet-side branch point J2 of the first oil filter 27.
The hydraulic pipe pl3 as one of the pipes is connected to a P port of the servo valve 25 responsible for a steam flow amount control function of the steam valve 200. The servo valve 25 accommodates a movable spool (reel-type shaft) inside a sleeve (tube) having inlet and outlet ports. By receiving a valve position control signal transmitted from a turbine control apparatus (not shown) by a coil 25C, the spool position is controlled. A pilot oil of the servo valve 25 is supplied via the second oil filter 28.
The valve position control signal from the turbine control apparatus (not shown) is input to the coil 25C. Based on the valve position control signal, the hydraulic oil 26 supplied to the P port from the hydraulic pipe pl3 reaches a branch point J3 via a B port.
The hydraulic oil 26 is supplied from the branch point J3 to the lower cylinder 204 of the piston 202 via a hydraulic pipe pl9. At the same time, the hydraulic oil 26 is also supplied to A ports of cartridge valves 29 and 30 via a hydraulic pipe pl10. The piston 202 of the main steam stop valve 200 operates to be opened and closed by the hydraulic oil 26 that has passed the servo valve 25.
On the other hand, the hydraulic pipe pl4 as the other one of the pipes split at the branch point J2 described above is additionally split into two hydraulic pipes pl5 and pl6 at a branch point J4. The hydraulic pipe pl5 is connected to a P port of the high-speed operation electromagnetic valve 21, and the hydraulic pipe pl6 is connected to a P port of the high-speed operation electromagnetic valve 22. The high-speed operation electromagnetic valves 21 and 22 are structured as a “3-port 2-position single-action electromagnetic valve” that includes a sleeve, 3 inlet and outlet ports provided in the sleeve, and a spool that is movably accommodated in the sleeve.
The high-speed operation electromagnetic valves 21 and 22 are important apparatuses for blocking the steam (steam energy) that enters the steam turbine when any anomaly (abnormality) occurs in the steam turbine. Therefore, the high-speed operation electromagnetic valves 21 and 22 constantly maintain an excitation state when the steam turbine is driven normally and are put to a non-excitation state at the time an anomaly (abnormality) occurs. Further, an anomaly (abnormality) signal to the high-speed operation electromagnetic valve 21 is applied to duplexed excitation coils 23a and 23b from a sequence circuit (not shown). Similarly, an anomaly signal to the high-speed operation electromagnetic valve 22 is applied to duplexed excitation coils 24a and 24b from a sequence circuit (not shown).
As described above, during normal drive of the steam turbine, the excitation coils 23a, 23b, 24a, and 24b of the high-speed operation electromagnetic valves 21 and 22 are constantly in an excitation state. Therefore, the hydraulic oil 26 passes the high-speed operation electromagnetic valves 21 and 22 from the P port to the A port. After that, the hydraulic oil 26 is supplied to the secondary side of the cartridge valves 29 and 30 attached to the high-speed operation electromagnetic valves 21 and 22, respectively, via hydraulic pipes pl13 and pl14. It should be noted that the B ports of the cartridge valves 29 and 30 are connected to the port of the upper cylinder 205 of the hydraulic drive apparatus 20 and also connected to the T port of the servo valve 25 via the hydraulic pipe pl7.
The hydraulic oil 26 that has passed through the servo valve 25 and been supplied to the A ports on the primary side of the cartridge valves 29 and 30 and the hydraulic oil 26 that has passed the P and A ports of the high-speed operation electromagnetic valves 21 and 22 from the hydraulic pipes pl5 and pl6 and been supplied to the secondary side of the cartridge valves 29 and 30 simultaneously act on the valving elements 31 and 32 of the cartridge valves 29 and 30. Therefore, forces that act on both sides of the valving elements 31 and 32 are balanced. As a result, the valving elements 31 and 32 of the cartridge valves 29 and 30 do not move.
Here, assuming that the anomaly detection portion of the protection apparatus of the steam turbine (not shown) has detected an anomaly, an anomaly signal is output from the anomaly detection portion and electrically transmitted to the coils 23a, 23b, 24a, and 24b of the high-speed operation electromagnetic valves 21 and 22 provided in the hydraulic drive apparatus 20 of the steam valve 200 shown in FIG. 4 via a sequence circuit (not shown).
When input with the anomaly signal, the coils 23a, 23b, 24a, and 24b of the high-speed operation electromagnetic valves 21 and 22 invert to a non-excitation state from the previous constant excitation state. By the inversion of the high-speed operation electromagnetic valves 21 and 22, the passage of the hydraulic oil 26 is switched. Before the switch, the hydraulic oil 26 passes the high-speed operation electromagnetic valves 21 and 22 from the P port to the A port and is supplied to the secondary side of the cartridge valves 29 and 30 via the hydraulic pipes pl13 and pl14. After the switch, the hydraulic oil 26 is discharged to an oil tank (not shown) via the hydraulic pipe pl8 and an oil-drain port 33.
Therefore, the valving elements 31 and 32 are pushed back by a hydraulic force of the hydraulic oil 26 supplied to the primary side from the hydraulic pipe pl10 via the servo valve 25 in the cartridge valves 29 and 30, and the A ports are opened. As a result, the hydraulic oil 26 accumulated in the lower cylinder 204 of the piston 202 reaches the A ports of the cartridge valves 29 and 30 via the hydraulic pipes pl9 and pl10 and discharged from the B ports of the cartridge valves 29 and 30. Consequently, the steam valve 200 closes.
At this time, the B ports of the cartridge valves 29 and 30 are connected to the port of the upper cylinder 205 located at an upper portion of the piston 202 of the hydraulic drive apparatus 20 by the hydraulic pipe pl7. Therefore, the hydraulic oil from the B ports of the cartridge valves 29 and 30 enters the upper cylinder 205. The hydraulic oil 26 that has entered the upper cylinder 205 is discharged to the oil tank (not shown) from the upper cylinder 205 of the piston 202 via the hydraulic pipe pl8 and the oil-drain port 33.
As described above, the hydraulic oil 26 accumulated in the lower cylinder 204 of the piston 202 in the hydraulic cylinder 203 temporarily enters the upper cylinder 205 of the piston 202. As a result, an action to press down the piston 202 occurs. In addition, since the upper cylinder 205 acts as an oil tank, the steam valve 200 can be more-rapidly and positively closed.
It should be noted that since reset springs 34 and 35 of the valving elements 31 and 32 are incorporated on the secondary side of the cartridge valves 29 and 30, if the hydraulic pressure of the A ports of the cartridge valves 29 and 30 is eliminated, the valving elements 31 and 32 of the cartridge valves 29 and 30 automatically return to a fully-closed state so as to block the A ports by the forces of the reset springs 34 and 35.
The hydraulic drive apparatus 20 of the steam valve 200 shown in FIG. 4 includes the servo valve 25 and controls the valve position of the main valve 201. It should be noted that the main valve may be simply turned ON and OFF depending on the purpose of the steam valve.
FIG. 5 is a structural diagram of a drive apparatus 40 of a steam valve 300 of the related art having the ON/OFF function. It should be noted that in FIG. 5, components having the same functions as those of FIG. 4 are denoted by the same symbols, and overlapping descriptions will be omitted as appropriate.
In FIG. 5, the steam valve 300 includes a main valve 301, a piston 302, a hydraulic cylinder 303, a lower cylinder 304, an upper cylinder 305, and a hydraulic system 306. The hydraulic cylinder 303 is a double-action type and the inside thereof is sectioned into the lower cylinder (valve-open-side chamber) 304 and the upper cylinder (valve-close-side chamber) 305 by the piston 302. The hydraulic cylinder 303 includes, on both the valve-open side and the valve-close side, inlet and outlet ports for a hydraulic oil. The hydraulic system 306 is equipped with a hydraulic pipe (also called oil passage (or passage)) and various valves and connects the lower cylinder 304 and the upper cylinder 305 to a hydraulic pressure generator and an oil tank (not shown). It should be noted that the piston 302, the hydraulic cylinder 303, and the hydraulic system 306 constitute the hydraulic drive apparatus 40 of the steam valve 300.
Points of the hydraulic system 306 shown in FIG. 5 different from those of the hydraulic system 206 shown in FIG. 4 are as follows. Specifically, the second oil filter 28 adopted in FIG. 4 is removed, and the servo valve 25 is replaced with a test electromagnetic valve 36 (also called third electromagnetic valve). The test electromagnetic valve 36 is operated in a non-excitation state (i.e., constant non-excitation state) during normal drive.
As in the servo valve 25, in the test electromagnetic valve 36, a position of a spool movably accommodated in a sleeve having inlet/outlet ports is controlled by a coil. At a time a valve test is carried out for preventing an adhesion of a valve shaft of the steam valve 300 from occurring during normal drive, a simulation signal is transmitted from a test apparatus (not shown) to a coil 36C of the test electromagnetic valve 36. Based on the simulation signal, the coil 36C is excited, and the port is switched. By being connected to the hydraulic pipe pl7 via the A port of the test electromagnetic valve 36, the hydraulic pipe pl9 is connected to the port of the upper cylinder 305.
Accordingly, the oil in the lower cylinder 304 of the piston 302 is gradually discharged from the oil-drain port 33 via the hydraulic pipes pl9 and pl7, the upper cylinder 305, and the hydraulic pipe pl8. As a result, the main valve 301 of the steam valve 300 is closed. After the main valve 301 of the steam valve 300 is fully closed, the test electromagnetic valve 36 is inverted to a non-excitation state from an excitation state. Consequently, the main valve 301 gradually opens, and the valve test ends.
If inadequate components in the hydraulic drive apparatus can be replaced with adequate components without stopping the steam turbine in normal drive, damages that occur can be minimalized.
As described above, the hydraulic pipes of the steam valve apparatus used in the steam turbine is a highly-reliable hydraulic system. However, the steam valve apparatus of the related art may not operate normally when a feature failure or operation failure occurs in the servo valve or the test electromagnetic valve during normal drive, for example.
A high-pressure hydraulic oil is constantly supplied to the hydraulic pipes of the steam valve apparatus of the related art. Therefore, the hydraulic oil scatters when a part of the hydraulic pipes is opened to replace inadequate components with adequate components. For the reason described above, it has been difficult to remove inadequate components and replace them with adequate components during normal drive of the steam turbine in the hydraulic pipes of the steam valve apparatus of the related art.
In this embodiment, inadequate components can be removed and replaced with adequate components during normal drive of a turbo machine such as the steam turbine. As a result, a maintenance property of the steam valve apparatus is improved.